Transcript Organic Compounds

Unit 3
Organic Chemistry
Chemistry 2202
Introduction

Organic Chemistry is the study of the
molecular compounds of carbon.
eg. CH4

CH3OH
CH3NH2
Organic compounds exclude oxides
of carbon and ions containing carbon.
ie. CO
CO2
KCN CaCO3
are NOT organic compounds!!
History of Organic Chemistry
Started when medicine men extracted
chemicals from plants and animals as
treatments and cures
 First defined as a branch of modern
science in the early 1800's by Jon
Jacob Berzelius

Berzelius believed in Vitalism organic compounds could only
originate from living organisms
through the action of some vital force
 organic compounds originate in living
or once-living matter
 inorganic compounds come from
"mineral" or non-living matter


In 1828, Friedrich Wöhler
discovered that urea - an organic
compound - could be made by
heating ammonium cyanate (an
inorganic compound).
NH4OCN(aq)  (NH2)2CO(s)
inorganic
organic
What’s this?
(NH2) 2CO - (NH2)2CO
di-urea
organic chemistry branched into
disciplines such as polymer
chemistry, pharmacology,
bioengineering and petro-chemistry
 98% of all known compounds are
organic


The huge number of organic
compounds is due mainly to the
ability of carbon atoms to form stable
chains, branched chains, rings,
branched rings, multiple rings, and
multiple bonds (double and triple
bonds) to itself and to many other
non-metal atoms.

Some more Organic notes
Sources of Organic Compounds
1. Carbonized Organic Matter
- fossil fuels such as coal, oil, and
natural gas
- basis for the petrochemical industry
2. Living Organisms
eg: - penicillin from mold
- ASA from the bark of a willow tree
3. Invention
- antibiotics, aspirin, vanilla flavoring,
and heart drugs are manufactured
from organic starting materials
- plastics
Structural Isomers

Structures that have the same molecular
formula but different structural formulas
are called structural isomers
eg. C4H10
Practice: Draw all structural isomers
of C5H12 and C6H14
Structural Isomers

structural isomers have the same
chemical formula but have different
chemical and physical properties.
Classifying Organic Compounds
Organic
Compounds
Hydrocarbon
Derivatives
Hydrocarbons
Aliphatic
AlkAnes
Aromatic
(benzene based)
•
•
•
•
•
AlkEnes
•
•
AlkYnes
•
•
Alcohols
Ethers
Aldehydes
Ketones
Carboxylic Acids
Alkyl Halides
Esters
Amines
Amides
hydrocarbons consist of carbon
and hydrogen atoms only
eg. Methane - CH4
 hydrocarbon derivatives have one
or more hydrogen atoms replaced by
another nonmetallic atom
eg. bromomethane - CH3Br
methanol - CH3OH

aliphatic hydrocarbons have
carbon atoms bonded in chains or
rings with only single, double, or
triple bonds
 aromatic hydrocarbons contain at
least one 6 carbon benzene ring

Aliphatic Hydrocarbons
1. Alkanes

Alkanes are hydrocarbons that have
only single bonds between carbon
atoms

general formula CnH2n+2
eg. C3H8
C6H14
IUPAC
prefixes
Prefix
meth
eth
prop
but
pent
hex
hept
oct
non
dec
# of carbon
atoms
1
2
3
4
5
6
7
8
9
10
Complete this methane
ethane
table for the
first 10 alkanes propane
CH4
A series of compounds which differ
by the same structural unit is called
a homologous series
eg. each alkane increases by CH2
What is the next member of this
homologous series?
SiO2
Si2O3
Si3O4
_____

Representing Alkanes (4 ways)
1. Structural formulas
eg. propane
H
H
H
H–C–C–C–H
H
H
H

Hydrogen atoms may be omitted
from structural formulas
eg. propane
–C–C–C–
2. Condensed Structural Formula
eg. propane
CH3-CH2-CH3
3. Line Structural Diagrams
eg: propane
(the endpoint of each segment is a
carbon atom)
4. Expanded Molecular Formulas
eg. propane
CH3CH2CH3
p. 333
Alkyl Groups

An alkyl group has one less hydrogen
than an alkane.
General Formula: CnH2n + 1
 To name an alkyl group, use the
prefix to indicate the # of carbon
atoms followed by the suffix –yl
eg. -C7H15 heptyl

Alkyl Groups
methyl -CH3
ethyl -C2H5 or -CH2CH3
propyl -C3H7 or -CH2CH2CH3
Alkyl Groups

Branched alkanes are alkanes
that contain one or more alkyl
groups
eg.
Naming Branched Alkanes
1. Find
the longest continuous chain of
carbons(parent chain) and name it
using the alkane name.
2. Number
the carbons in the parent
chain starting from the end closest to
branching. These numbers will
indicate the location of alkyl groups.
Naming Branched Alkanes
3.
List the alkyl groups in alphabetical
order. Use Latin prefixes if an alkyl
group occurs more than once.
(di = 2, tri = 3, tetra = 4, etc.)
4.
Use a number to show the location of
each alkyl group on the parent.
Naming Branched Alkanes
5.
Use commas to separate numbers,
and hyphens to separate numbers
and letters.
Naming Branched Alkanes
eg.
ethyl
7
6
5
4
3
2
1
methyl
4-ethyl-3-methylheptane
Naming Branched Alkanes
Practice:

p. 336 - 339 #’s 5 – 11
(Answers on p. 375)
Alkenes and Alkynes
 saturated
hydrocarbons contain
only single bonds between carbon
atoms
eg. alkanes
 saturated hydrocarbons have the
maximum number of hydrogen
atoms bonded to carbon atoms
Alkenes and Alkynes

unsaturated hydrocarbons contain
double or triple bonds between
carbon atoms
eg. alkenes and alkynes
Alkenes and Alkynes
 General
Formulas:
At least one
double bond
 Alkenes CnH2n
 Alkynes CnH2n - 2
At least one
triple bond
Naming Alkenes and Alkynes
1.
2.
Name the longest continuous
chain that contains the
double/triple bond.
Use the smallest possible
number to indicate the position of
the double or triple bond.
Naming Alkenes and Alkynes
3.
4.
Branches are named using the
same rules for alkanes.
Number the branches starting at
the same end used to number
the multiple bond.
Naming Alkenes and Alkynes
p. 347 #’s 17 - 19
 p. 354 #’s 28 & 29

Cyclic Hydrocarbons

Pp. 356 – 358
 questions 30 & 31
3-ethyl-1-methylcyclopentane
1-ethyl-3-methylcyclopentane
cyclopentane
2
1
ethyl
3
methyl
methyl
1,2,3,4-tetramethylcyclohexane
Aromatic Compounds
Aromatic hydrocarbons contain at least
one benzene ring.
 The formula for benzene, C6H6 , was
determined by Michael Faraday in 1825.
 The structural formula was determined by
August Kekulé in 1865.

Aromatic Compounds
Proposed formula:
Conflicting Evidence
C=C double bonds are shorter than CC single bonds. X-ray crystallography
shows that all C-C bonds in benzene
are the same length.
 Benzene reacts like an alkane, not like
an alkene.

Modified structure
Kekulé proposed a resonance
structure for benzene.
 The resonance structure is an
average of the electron distributions.

Aromatic Compounds
or
Aromatic Compounds
bonding electrons, once believed to be
in double bonds, are delocalized and
shared equally over the 6 carbon atoms
 the bonds in benzene are like “1½”
bonds – somewhere between single
and double.

Naming Aromatic Compounds
an alkyl benzene has one or more H
atoms replaced by an alkyl group.
 name the alkyl groups, using
numbers where necessary, followed
by the word benzene.

Aromatic Compounds
methylbenzene
ethylbenzene
propylbenzene
Aromatic Compounds
1,3-dimethylbenzene
1,4-dimethylbenzene
1,2-dimethylbenzene
Aromatic Compounds
ortho- means positions 1 and 2 and is
represented by "o"
 meta- means positions 1 and 3 and is
represented by "m"
 para- means positions 1 and 4 and is
represented by "p"

Aromatic Compounds
m-dimethylbenzene
p-dimethylbenzene
o-dimethylbenzene
Aromatic Compounds
Benzene is treated as a branch if it is
not attached to the terminal carbon of
an alkyl group
 Benzene as a branch is called phenyl

Aromatic Compounds
CH3
CH2
CH2
CH3 CH CH3
2-phenylpropane
propylbenzene
Aromatic Compounds
CH3 CH2 CH2 CH CH CH3
CH2
CH3
Aromatic Compounds
CH3
CH2
CH2 CH3
CH3 CH2 CH2 CH CH2 CH CH CH3
Aromatic Compounds

p. 361 #’s 32 – 35
Hydrocarbons Practice
pp. 363, 364
#’s 4 – 9
Test!!

cis and trans isomers (p. 348)
Properties of aliphatic
hydrocarbons
Because they are nonpolar, all
hydrocarbons are insoluble in water.
 The boiling point of alkanes is somewhat
higher than alkenes but lower than
alkynes.
 As the number of atoms in the
hydrocarbon molecule increases, the
boiling point increases.

Reactions
Complete the aliphatic hydrocarbons
worksheet using these references:
a) complete combustion (p. 340)
b) incomplete combustion (p. 340)
c) substitution reaction (p. 344, 362)
d) addition reaction (p. 349)
Hydrocarbon Derivatives
hydrocarbon derivative - contains
other nonmetal atoms such as O, N, or
halogen atoms.
 9 types
 functional group - the reactive group
of atoms that gives a family of
derivatives its distinct properties

Hydrocarbon Derivatives

The general formula for a derivative is
R - functional group
where R stands for any alkyl group.
Hydrocarbon Derivatives
eg. ALCOHOLS R-OH
ethanol
C2H5OH
propanol
C3H7OH
CARBOXYLIC ACIDS R-COOH
ethanoic acid
CH3COOH
propanoic acid C2H5COOH
1. Alcohols

Have the hydroxyl functional group
General Formula: R - OH
Naming Alcohols (p. 387)

The parent alkane is the longest chain
that has an -OH group
Replace the last -e in the alkane name
with the suffix -ol.
 Add a number to indicate the location of
the -OH group.

H
H
C
O
H
methanol
H
H
H
H
C
C
H
H
O
H
ethanol
H
eg.
H
H
H
C
C
C
H
H
H
H
H
H
O
H
C
C
C
H
H
H
H
O
H
Properties of Alcohols (p. 389)
Alcohols have H-bonding which
makes their mp and bp higher than
the corresponding alkane.
 Polarity decreases as the # of carbon
atoms increases
 Long chain alcohols are less soluble
in water than short chain alcohols.

Reactions of alcohols
Combustion
R-OH + O2 → CO2 + H2O
eg. Write the equation for the burning
of butanol.
Reactions of alcohols
Substitution
R-OH + H-X → R-X + H2O
eg. Use structural formulas to show
the reaction between 2-pentanol and
HBr.
Reactions of alcohols
Elimination (Dehydration)
eg.
H H H
H C C C O H
H H H
H2SO4
H H H
H C C C H
H
+ H2O
P. 393 16 a), d), 18 a), b), d) & e)
(Draw structural formulas for the
products in #18)
2. Ethers
 Composed
of two alkyl groups
bonded to an oxygen atom.
 General Formula: R1-O-R2
 Naming ethers: p. 395
 IUPAC name
 Common name
H
H
C
O
H
H
H
H
C
C
H
H
H
H
H
C
C
C
H
H
H
O
H
H
H
H
H
C
C
C
C
H
H
H
H
H
H
H
H
C
C
H
H
O
H
H
C
C
H
H
H
P. 395, 396 #’s 20 – 23
Worksheet: Ethers
3. Aldehydes (p. 402)
 Contain
a carbonyl functional
group at the end of a carbon chain.
O
General Formula:
R-C
H
Naming:
 Use the alkane name for the
longest continuous chain.
 Remove the –e and add the suffix
–al
H
H
H
H
eg.
H
C
C
C
H
H
H
C
O
4. Ketones (p. 402)
a carbonyl functional group
in the ‘middle’ of a carbon chain.
ie. NOT on carbon #1
General Formula:
=O
 Contain
R1-C- R2
Naming:
 Use the alkane name for the longest
continuous chain.
 Replace the –e with the suffix –one
 Use the smallest possible number for
the position of the C=O group.
H
H
H
O
H
Cp. 403
C #’sC28 - 31
C
H
HHandout:
H Aldehydes
H
and Ketones
H
H
H
H
O
H
C
C
C
C
C
H
H
H
H
H
5. Carboxylic Acids (p. 405)
=O
Contain a carboxyl functional group
ie. -COOH
General Formula:
AKA: Organic Acids
R1-C- OH
H
H
H
O
C
C
C
H
H
OH
HO
O
H
H
H
C
C
C
C
H
H
H
Text; p. 406 #’s 32 - 35
H
6. Alkyl Halides (p. 390, 391)
Contain at least one halogen atom
General Formula: R – X
(X is F, Cl, Br, or I)
Br
Br
C
C
C
C
H
H
Br
H
H
H
H
H
H
H
Cl
Br
Br
H
C
C
C
C
C
H
Br
H
H
H
Text; p. 406 #’s 32 - 35
Text; p. 391 #’s 12 – 15
Worksheet: Organic # 8
Br
Elimination - Alcohols
eg.
H H H
H C C C O H
H H H
H2SO4
Δ
H H H
H C C C H
H
+ H2O
Elimination – Alkyl Halides
eg.
H
H
H
H
C
C
C
H
H
H
I
+ OH- →
H
H
H
H
C
C
C
H
H
+ H2O + Ip.393 #’s 18 c) and f)
7. Esters (pp. 410, 411)
=
Form when a carboxylic acid reacts with
an alcohol
General Formula:
O
R1-C- O-R2
Esterification Reaction:
carboxylic acid + alcohol → ester + water
Naming:
- the parent is named by replacing the
– oic acid ending from the acid with – oate
- the alcohol is identified by using the
corresponding alkyl group
pp. 411, 412 #’s 36 - 40
8. Amines (pp. 410, 411)
Form when a carboxylic acid reacts with
an alcohol
General Formula: R – NH2
Cracking & Reforming
‘Cracking‘ is a reaction that break long chain
hydrocarbons into smaller fragments.
eg.
decane + H2 → ethane + octane
Reactions – Organic Compounds
Combustion (p. 340)
Substitution (p. 344)
Esterification (p. 410)
Elimination (p. 390)
Cracking & Reforming
‘Reforming’ is a reaction that combines smaller
hydrocarbons to make long chain hydrocarbons
eg.
ethane + butane → hexane + H2
Review - Derivatives
pp. 400, 401
Omit:
1a), 2c) & d), 3b) & e), 5b),
8, 10b) & c), 11b) & d)
pp. 419, 420
Omit:
1g), 3d), 4a), 7, 8c), 10